Corona generator

ABSTRACT

A corona generator is formed of simple, bendable or flexible tubing and includes a plastic dielectric for simplicity and economy. A long length of tubing is formed into a convenient coil, and the tubing is arranged in several combinations including electrodes, plastic dielectric, and a gap where a corona discharge is formed and through which a gas is passed.

United States Patent [191 Burris June 26, 1973 1 1 CORONA GENERATOR [76] Inventor: W. Alan Burris, 7 East Jefferson Circle, Pittsford, NY. 14534 [22 Filed: May 11, 1972 21 Appl. No.: 252,207

3,387,218 6/1968 Friichtenicht et a1. 317/4 Primary Examiner-L. T. Hix AttorneyCumpston, Shaw & Stephens [57] ABSTRACT A corona generator is formed of simple, bendable or flexible tubing and includes a plastic dielectric for simplicity and economy. A long length of tubing is formed into a convenient coil, and the tubing is arranged in several combinations including electrodes, plastic dielectric, and a gap where a corona discharge is formed and through which a gas is passed.

35 Claims, 12 Drawing Figures HIGH VOLTAGE PAIENIEflauuzs ms 3, 742.301

COMPRESSOR HIGH LTAGE S U CE VOLTAG E FIG 3 HIGH VOLTAGE f SOURCE PATENTED 9 3, 742.301

SHEEI 2 0F 3 HIGH H VOLTAGE VO GE PAIENIEDJUIIZB I973 HIGH VOLTAGE HIGH VOLTAGE HIGH VOLTAGE HIGH VOLTAGE CORONA GENERATOR THE INVENTIVE IMPROVEMENT Many corona generators have been suggested, and one common use for such equipment is generating ozone, although corona generators are also useful for other processes. Corona generators have generally used parallel plate or concentric tube electrodes separated by a solid dielectric material and a gap through which a gas is passed. For various reasons, corona generators have been expensive, partly because of intricate construction and the expensive, high-voltage sources and expensive materials they have required.

The invention involves recognition ofa way to make a corona generator that is far cheaper than any known corona generators, partly from the discovery that plastic is a workable dielectric. The invention seeks simplicity, economy, and a substantial reduction in production costs for a corona generator. The invention also aims at construction of a corona generator out of commonly available and inexpensive materials while maintaining reasonable operating efficiency.

SUMMARY OF THE INVENTION One preferred form of the inventive generator uses a long length of readily bendable tubing formed of electrically conductive material with a long length of plastic-covered electrical conductor inside the tubing and extending substantially the full length of the tubing. The inside diameter of the tubing exceeds the outside diameter of the plastic-covered conductor by from 0.5 millimeters. A gas is forced through the tubing, and a high voltage is applied to the plastic-covered conductor relative to the tubing. The tubing is curved into a convenient shape for operation.

Another form of the inventive generator uses a long length of flexible, plastic tubing surrounded by an electrically conductive material. A long length of electric conductor is in the plastic tubing and extends substantially the full length of the plastic tubing. The inside diameter of the plastic tubing exceeds the outside diameter of the conductor by from 0.5 5 millimeters. A gas is forced through the plastic tubing, and a high voltage is applied to the conductor relative to the conductive material. The plastic tubing is curved into a convenient shape for operation.

DRAWINGS FIG. 1 is a partially schematic view of one preferred embodiment of the inventive corona generator;

FIG. 2 is a schematic view of another preferred embodiment of the inventive corona generator; and

FIGS. 3 12 are partially schematic, cross-sectional views of various tubing arrangements for the inventive generator.

DETAILED DESCRIPTION The corona generators of FIGS. 1 and 2 are each arranged for generating ozone which is bubbled into a water tank for a water purefication system. However, the inventive corona generator can be used for other processes, and FIGS. 1 and 2 illustrate only one of many applications for such equipment. The FIG. 1 arrangement generates a corona in a coiled tubing outside of water tank 11, and the arrangement of FIG. 2 generates a corona in a coiled tubing 12 inside water tank 13. Each arrangement uses an air compressor 14 5 join in a T-connection 17 leading to the tubing coils 10 and 12.

Tubings 10 and 12 are each flexible or bendable enough to be curved into convenient shapes such as coils or loops, and they can run to substantial lengths such as 10 meters or more. A corona discharge occurs substantially throughout the length of tubings l0 and 12 to help considerably in cooling the generator. Either tubing can be submerged in liquid to facilitate cooling, and either can be laid in a pipeline, tank, or other container in coils, loops or bends.

The construction of tubings 10 and 12 is important to achieve the economy sought by the invention. Preferably simple, economical and readily available materials are arranged so that the corona generator is cheap and efficient and so the dielectric material between the electrodes does not break down. The prior art has proposed many complicated arrangements for electrodes and dielectric materials in corona generators, but the inventive generator is far simpler and cheaper and still efficient. Some of the various acceptable constructions for tubings 10 and 12 are best shown in FIGS. 3 12.

Tubing 10 of FIG. 3 is the type used in the generator of FIG. 1 and includes a length of electrically conducting tubing 10 formed preferably of aluminum, copper, or stainless steel so that tubing 10 is readily bendable and can easily be coiled and uncoiled. Suitable tubing is widely available for other purposes, and aluminum tubing is preferred for ozone generating. Inside tubing 10 is a conductor wire 17 encased in a coating of plastic 18. Wire 17 can be a single or multi-strand conductor in generally available form with a plastic insulator coating 18 preferably of a material having high dielectric strength, a high dielectric constant, and high ozone resistance. For example, polyvinyl chloride and many polyethylene, polyurethane, silicone rubber, other plastic insulator materials are acceptable.

The inside diameter of tubing 10 exceeds the outside diameter of plastic coating 18 by from 0.5 5 millimeters, and preferably by about 1.5 millimeters to form an efficient-sized gap for the corona discharge. Tubing l0 and conductor 17 form the electrodes for the generator, and a high potential difference is applied between tubing 10 and conductor 17. For safety and convenience, tubing 10 is preferably grounded and a high voltage of preferably 5,000 to 10,000 volts is applied to conductor 17. This creates a corona discharge in the gap between plastic coating 18 and tubing 10, so that a gas can be passed through such gap along the length of tubing 10 for processing.

Experience has shown that wire 17 with its plastic coating 18 can be laid loosely inside tube 10 and free to contact the inside surface of tube 10 and still form a very satisfactory corona generator. However, wire 17 can be centered inside of tube 10, and one way of doing this is shown in FIG. 8 where plastic coating 18 has extruded fins l9 bridging the gap between plastic 18 and tubing 10. Also, plastic spacer strand 31 can be wrapped in a helix around plastic 18 to center it within tubing 10 as shown in FIG. 10.

Tubing 12 of FIG. 4 is the type used in the generator of FIG. 2 and includes a substantial length of flexible plastic tubing 12 preferably formed of polyvinyl chloride, polyethylene, polyurethane, silicone rubber or some other plastic insulator having high dielectric strength, a high dielectric constant, and high ozone resistance. A metal conductor 20 is arranged inside tubing 12 and extends for substantially the full length of tubing 12, which can amount to 10 meters or more, for example. The inside diameter of tubing 12 exceeds the outside diameter of conductor 20 by 0.5 millimeters, and preferably by about 1.5 millimeters. Water 21 surrounding tubing 12 provides one of the electrodes, and also helps cool tubing 12. Water 21 is grounded as illustrated, and a high voltage of preferably 5,000 to 10,000 volts is applied to conductor 20 to produce a corona in the gap between conductor 20 and tubing 12 along the length of tubing 12 so that a gas passed through the gap is processed. Another conductive liquid can be substituted for water 21, or a metallic or other electrode can be arranged outside tubing 12 if desired.

FIG. 5 showns an embodiment similar to the embodiment of FIG. 3, except that tubing has a plastic coating 22 on its inside, and conductor 23 is arranged inside plastic tube 22. Conductor 23 can be a solid rod as illustrated, or a hollow tube such as shown in FIG. 4. The preferred gaps and voltages are preferably as previously described.

The embodiment of FIG. 6 is also similar to FIG. 3 in using tubing 10, but the internal electrode is formed as a length of plastic tubing 24 filled with a conductive liquid 25. The high voltage is applied to liquid 25, and liquid 25 can be circulated along the length of tubing 24 if desired. Again, preferred gaps and voltages are as previously described.

The embodiment of FIG. '7 has two corona gaps. It uses plastic tubing 12 immersed in a conductive liquid 21 and having an internal conductive tubing as described above relative to FIG. 4. It adds a conductive wire 26 having a plastic coating 27 and arranged inside conductor tube 20 with a 0.5 5 millimeter gap for an additional corona discharge. A gas is passed between tubing 20 and tubing 12, and also between tubing 20 and the plastic coating 27 of wire 26. Then if a high voltage is applied to conductor 20, and conductor 26 is held at the ground potential of the surrounding liquid 21, two corona discharges occur on either side of conductor 20 so that a gas can be passed through each of these for processing.

The embodiment of FIG. 9 uses a bendable metal tubing 28 having a plastic liner 29 with extruded internal projections 30 centering a metal tubular conductor 32 inside tubing 23. A high voltage is applied to conductor 32, and tubing 28 is grounded to produce a corona discharge in the gaps between the projections 30 of plastic liner 29.

The embodiment of FIG. 10 uses a bendable metal tubing 33 carrying a conductor 34 having a plastic insulating covering 35, and a plastic strand 31 is formed in a helix around plastic insulator 35 to center conductor 34 within tubing 33. A high voltage is applied to conductor 34, and tubing 33 is grounded to produce a corona discharge in the gap formed along the path of helical strand 31.

In the embodiment of FIG. 11, a bendable metal tubing 36 is submerged in a cooling and grounded liquid 37 and has a plastic tubular lining 38. A conductor 39 has an extruded plastic coating 40 that has extruded fins 41 centering conductor 39 within plastic tubing 38.

Tubing 38 and covering 40 form a pair of dielectrics across the gap set by projections 41 so that when a high voltage is applied to conductor 39, and tubing 36 is grounded, a corona discharge occurs in such gap. Separated dielectrics can be arranged in many other ways to form a corona discharge gap.

In the embodiment of FIG. 12, a plastic tubing 42 contains a pair of conductors 43 and 44 each having respective plastic insulating coatings 45 and 46. A gas is passed through tubing 42 in the space left by conductors 43 and 44 and their insulator coatings 45 and 46, so that when a high voltage is applied to conductor 43 relative to conductor 44, a corona discharge occurs within tubing 42. With such an arrangement, tubing 42 merely contains the processed gas and the conductors and can be formed of any convenient material.

Persons wishing to practice the invention should remember that other embodiments and variations can be adapted to particular circumstances. Even though one point of view is necessarily chosen in describing and de fining the invention, this should not inhibit broader or related embodiments going beyond the semantic orientation of this application but falling within the spirit of the invention. For example, those skilled in the art will appreciate the many materials and electrode and gap arrangements possibly constructed of simple and economical tubing materials within the spirit of the invention. Different sizes, thicknesses, and plastic and metallic materials can be readily applied by those skilled in the art.

I claim:

1. In a tubular-type corona generator, the improvement comprising:

a. a long length of readily bendable tubing formed of electrically conductive metal;

b. a long length of plastic-covered electrical conductor inside said tubing and extending substantially the full length of said tubing;

c. the inside diameter of said tubing exceeding the outside diameter of said plastic-covered conductor by from 0.5 5 millimeters;

d. means for forcing a gas through said tubing;

e. means for applying a high voltage to said plasticcovered conductor relative to said tubing; and

1'. said tubing being curved into a convenient shape.

2. The generator of claim 1 wherein said plastic covering for said conductor has a high dielectric strength and high ozone resistance.

3. The generator of claim 1 wherein said plasticcovered conductor is loose in said tube and free to touch the inside of said tube.

4. The generator of claim 1 wherein said tubing is selected from the group consisting of aluminum, copper and stainless steel.

5. The generator of claim 1 including a container of liquid, means for discharging gas from said tubing into said liquid, and a check valve arranged between said liquid and said tubing.

6. The generator of claim 5 wherein said tubing is immersed in said liquid.

7. The generator of claim 1 wherein said plastic covering said conductor has extruded fins centering said conductor within said tubing.

3. The generator of claim 1 including a helical plastic strand around said plastic-covered conductor to center said conductor within said tubing.

9. The generator of claim 1 including means for immersing said tubing in a cooling liquid.

10. In a tubular-type corona generator, the improvement comprising:

a. a long length of readily bendable tubing formed of electrically conductive metal;

b. a long length of plastic tubing inside said metal tubing and extending substantially the full length of said metal tubing;

c. the inside diameter of said metal tubing exceeding the outside diameter of said plastic tubing by from 0.5 5 millimeters;

d. meansfor forcing gas through said metal tubing;

e. electric conductive material inside said plastic tubing and extending substantially the full length of said plastic tubing;

f. means for applying a high-voltage to said conductive material inside said plastic tubing relative to said metal tubing; and

g. said metal tubing being curved into a convenient shape.

11. The generator of claim wherein said conductive material inside said plastic tubing is an electrically conductive liquid.

12. The generator of claim 10 wherein said conductive material inside said plastic tubing is a metallic conductor.

13. The generator of claim 10 wherein said plastic tubing has extruded fins centering said plastic tubing within said metal tubing.

14. The generator of claim 10 including a helical plastic strand around said plastic tubing to center said plastic tubing in said metal tubing.

15. The generator of claim 10 including means for immersing said metal tubing in liquid.

16. In a tubular-type corona generator, the improve ment comprising:

a. an electrically conductive material;

b. a long length of flexible plastic tubing surrounded by said electrically conductive material;

c. a long length of electric conductor in said plastic tubing and extending substantially the full length of said plastic tubing;

d. the inside diameter of said plastic tubing exceeding the outside diameter of said conductor by from 0.5 5 millimeters.

e. means for forcing a gas through said plastic tubing;

f. means for applying a high voltage to said conductor relative to said conductive material; and

g. said plastic tubing being curved into a convenient shape.

17. The generator of claim 16 wherein said conductive material is water, and said plastic tubing is submerged in said water.

18. The generator of claim 17 including means for discharging said gas into said water.

19. The generator of claim 18 including a check valve at the discharge end of said tubing.

20. The generator of claim 16 wherein said conductor is loose in said plastic tubing and free to touch the inside of said plastic tubing.

21. The generator of claim 16 wherein said plastic tubing is formed of material having high dielectric strength and high ozone resistance.

22. The generator of claim 16 wherein said conductor is tubular.

23. The generator of claim 22 including a long length of plastic-covered electrical conductor inside said conductive tubing and extending substantially the full length of said conductive tubing, the inside diameter of said conductive tubing exceeding the outside diameter of said plastic-covered conductor by from 0.5 5 millimeters, means for forcing a gas through said conductive tubing, and means for maintaining said plasticcovered conductor at substantially the same voltage potential as said conductive material surrounding said plastic tubing.

24. The generator of claim 16 wherein said electric conductor is plastic-covered.

25. The generator of claim 16 wherein said electrically conductive material is a bendable metal sleeve surrounding said plastic tubing.

26. The generator of claim 16 wherein said electrically conductive material is liquid.

27. The generator of claim 26 wherein said electrically conductive material includes a container for said liquid.

28. The generator of claim 26 wherein said conductor in said plastic tubing is plastic-coated.

29. The generator of claim 16 including extruded, internal, plastic fins on said plastic tubing for centering said electric conductor in said plastic tubing.

30. The generator of claim 16 wherein said electric conductor in said plastic tubing has a plastic covering including extruded plastic fins centering said conductor in said plastic tubing.

31. The generator of claim 16 including a helical plastic strand centering said electrical conductor in said plastic tubing.

32. In a tubular-type corona generator, the improvement comprising:

a. a long length of readily bendable tubing;

b. a plurality of plastic-covered electrical conductors inside said tubing and extending substantially the full length of said tubing;

0. means for forcing a gas through said tubing;

d. means for applying a high voltage to one of said plastic-covered conductors relative to another of said plastic-covered conductors; and

e. said tubing being curved into a convenient shape.

33. The generator of claim 32 wherein said tubing is formed of flexible plastic material.

34. The generator of claim 32 wherein said plastic covering for said conductors has high dielectric strength and high resistance to ozone.

35. The generator of claim 32 including means for submerging said tubing in a liquid. 

1. In a tubular-type corona generator, the improvement comprising: a. a long length of readily bendable tubing formed of electrically conductive metal; b. a long length of plastic-covered electrical conductor inside said tubing and extending substantially the full length of said tubing; c. the inside diameter of said tubing exceeding the outside diameter of said plastic-covered conductor by from 0.5 - 5 millimeters; d. means for forcing a gas through said tubing; e. means for applying a high voltage to said plastic-covered conductor relative to said tubing; and f. said tubing being curved into a convenient shape.
 2. The generator of claim 1 wherein said plastic covering for said conductor has a high dielectric strength and high ozone resistance.
 3. The generator of claim 1 wherein said plastic-covered conductor is loose in said tube and free to touch the inside of said tube.
 4. The generator of claim 1 wherein said tubing is selected from the group consisting of aluminum, copper and stainless steel.
 5. The generator of claim 1 including a container of liquid, means for discharging gas from said tubing into said liquid, and a check valve arranged between said liquid and said tubing.
 6. The generator of claim 5 wherein said tubing is immersed in said liquid.
 7. The generator of claim 1 wherein said plastic covering said conductor has extruded fins centering said conductor within said tubing.
 8. The generator of claim 1 including a helical plastic strand around said plastic-covered conductor to center said conductor within said tubing.
 9. The generator of claim 1 including means for immersing said tubing in a cooling liquid.
 10. In a tubular-type corona generator, the improvement comprising: a. a long length of readily bendable tubing formed of electrically conductive metal; b. a long length of plastic tubing inside said metal tubing and extending substantially the full length of said metal tubing; c. the inside diameter of said metal tubing exceeding the outside diameter of said plastic tubing by from 0.5 - 5 millimeters; d. means for forcing gas through said metal tubing; e. electric conductive material inside said plastic tubing and extending substantially the full length of said plastic tubing; f. means for applying a high-voltage to said conductive material inside said plastic tubing relative to said metal tubing; and g. said metal tubing being curved into a convenient shape.
 11. The generator of claim 10 wherein said conductive material inside said plastic tubing is an electrically conductive liquid.
 12. The generator of claim 10 wherein said conductive material inside said plastic tubing is a metallic conductor.
 13. The generator of claim 10 wherein said plastic tubing has extruded fins centering said plastic tubing within said metal tubing.
 14. The generator of claim 10 including a helical plastic strand around said plastic tubing to center said plastic tubing in said metal tubing.
 15. The generator of claim 10 including means for immersing said metal tubing in liquid.
 16. In a tubular-type corona generator, the improvement comprising: a. an electrically conductive material; b. a long length of flexible plastic tubing surrounded by said electrically conductive material; c. a long length of electric conductor in said plastic tubing and extending substantially the full length oF said plastic tubing; d. the inside diameter of said plastic tubing exceeding the outside diameter of said conductor by from 0.5 - 5 millimeters. e. means for forcing a gas through said plastic tubing; f. means for applying a high voltage to said conductor relative to said conductive material; and g. said plastic tubing being curved into a convenient shape.
 17. The generator of claim 16 wherein said conductive material is water, and said plastic tubing is submerged in said water.
 18. The generator of claim 17 including means for discharging said gas into said water.
 19. The generator of claim 18 including a check valve at the discharge end of said tubing.
 20. The generator of claim 16 wherein said conductor is loose in said plastic tubing and free to touch the inside of said plastic tubing.
 21. The generator of claim 16 wherein said plastic tubing is formed of material having high dielectric strength and high ozone resistance.
 22. The generator of claim 16 wherein said conductor is tubular.
 23. The generator of claim 22 including a long length of plastic-covered electrical conductor inside said conductive tubing and extending substantially the full length of said conductive tubing, the inside diameter of said conductive tubing exceeding the outside diameter of said plastic-covered conductor by from 0.5 - 5 millimeters, means for forcing a gas through said conductive tubing, and means for maintaining said plastic-covered conductor at substantially the same voltage potential as said conductive material surrounding said plastic tubing.
 24. The generator of claim 16 wherein said electric conductor is plastic-covered.
 25. The generator of claim 16 wherein said electrically conductive material is a bendable metal sleeve surrounding said plastic tubing.
 26. The generator of claim 16 wherein said electrically conductive material is liquid.
 27. The generator of claim 26 wherein said electrically conductive material includes a container for said liquid.
 28. The generator of claim 26 wherein said conductor in said plastic tubing is plastic-coated.
 29. The generator of claim 16 including extruded, internal, plastic fins on said plastic tubing for centering said electric conductor in said plastic tubing.
 30. The generator of claim 16 wherein said electric conductor in said plastic tubing has a plastic covering including extruded plastic fins centering said conductor in said plastic tubing.
 31. The generator of claim 16 including a helical plastic strand centering said electrical conductor in said plastic tubing.
 32. In a tubular-type corona generator, the improvement comprising: a. a long length of readily bendable tubing; b. a plurality of plastic-covered electrical conductors inside said tubing and extending substantially the full length of said tubing; c. means for forcing a gas through said tubing; d. means for applying a high voltage to one of said plastic-covered conductors relative to another of said plastic-covered conductors; and e. said tubing being curved into a convenient shape.
 33. The generator of claim 32 wherein said tubing is formed of flexible plastic material.
 34. The generator of claim 32 wherein said plastic covering for said conductors has high dielectric strength and high resistance to ozone.
 35. The generator of claim 32 including means for submerging said tubing in a liquid. 